The facts
What atacamite actually is
The species behind atacamite is atacamite, Cu₂Cl(OH)₃; it forms in the orthorhombic system.
Cu²⁺ in a chloride hydroxide, giving deep emerald to blackish-green is responsible for the colour — and the chromophore, not the name, is what decides whether a colour is stable.
On the instruments it reads a refractive index of 1.831–1.880 and a specific gravity of about 3.75–3.78, with perfect {010} cleavage.
Where atacamite comes from
Commercial material comes from Atacama Desert (Chuquicamata and Mina La Farola), Chile, Wheal Gorland, Cornwall, England, Burra Burra, South Australia and Mount Gunson, South Australia.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How atacamite is treated
Untreated. Also forms as a corrosion product on bronze artefacts recovered from seawater, which is why archaeologists know the name. Confusable with malachite but does not effervesce in acid.
We state the treatment on every stone, including when the honest answer is that it cannot be determined. A treatment disclosed is a fact; a treatment discovered later is a refund.
What atacamite is confused with
Watch for Malachite, Brochantite, Dioptase and Olivenite — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.831–1.880 and specific gravity 3.75–3.78 settle most of it in a minute, and magnification settles the rest.
What atacamite is used for
The trades that buy atacamite are mineral collecting. They do not want the same thing, and they do not pay in the same unit.
We quote each application in the unit that trade actually buys in, by the specimen.
Durability and care
Hardness 3–3.5; cleavage perfect {010}. That combination decides what it can safely be set into.
Below about 5.5 a stone will be scratched by ordinary household dust, which is largely quartz. That does not make it unusable — it makes it a pendant, an earring or an object rather than a ring worn every day.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What atacamite costs
Expect roughly Specimens $30–$1,500, depending on quality.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is atacamite treated, and how?
Untreated. Also forms as a corrosion product on bronze artefacts recovered from seawater, which is why archaeologists know the name. Confusable with malachite but does not effervesce in acid.
Where does atacamite come from?
Atacama Desert (Chuquicamata and Mina La Farola), Chile, Wheal Gorland, Cornwall, England, Burra Burra, South Australia and Mount Gunson, South Australia. Origin affects price, so we name the locality rather than the country on every quote.
Is atacamite hard enough to wear every day?
Not really. At 3–3.5 on the Mohs scale it is softer than the quartz dust in ordinary household dirt, so it scratches with wear. It suits pendants, earrings and objects better than a daily ring.
How much does atacamite cost?
Indicatively Specimens $30–$1,500. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is atacamite confused with?
Most often Malachite, Brochantite, Dioptase and Olivenite. A refractive index of 1.831–1.880 and a specific gravity near 3.75–3.78 separate it quickly.
Related stones
Looking for atacamite?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about atacamite